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DNA-modified lanthanide-doped upconversion nanoparticles (DNA-UCNPs) that combine DNA's function and optical feature of UCNPs together have shown great promise in the fields of new material design, photonic devices, bioimaging, and disease treatment. However, challenges remain in precisely tethering and orientating the DNA strands on UCNP surface. Herein, we systematically investigate the sequence dependence of DNAs in their interactions with UCNPs, and reveal that poly-cytosine (poly-C) has specifically high affinity to UCNP surface. Based on this discovery, we develop a general approach to synthesize monodispersed DNA-UCNP conjugates using poly-C containing "diblock" DNA strands. High binding affinity of poly-C segment enables its competitive and firm tethering on the surfaces of UCNPs with different sizes, shapes, and luminescence. Consequently, the second block of used DNA strands with lower affinity would tightly and perpendicularly orientate on UCNP surface, making the DNA-UCNPs highly stable and monodispersed in aqueous solution. With complementary designed sequences, the dense layer of extruding DNA segments on UCNP surface allows the particles programmably assemble with other DNA-functionalized nanoparticles or DNA origamis through hybridizations, resulting in the formation of well-organized complex structures.
PMID: 32097523 [PubMed - as supplied by publisher]